As a defect inspection apparatus which detects a defect in a pattern of a semiconductor, there is known a defect inspection apparatus which compares a target part of image data for a pattern with its periphery to detect a defect.
However, when the pattern of the semiconductor is finer, the signal level of the defect is lower, and the detection of the defect is more difficult. Therefore, the increase of the sensitivity of a sensor for defect detection has been suggested.
However, when the sensitivity of the sensor for defect detection is increased, the sensor detects and recognizes natural radiation and others as defects, resulting in false defect recognition.
There has been a need for an apparatus capable of accurately detecting a defect of a subject such as a pattern.